Influence of CTO additives on microstructure and electrical properties of CCTO ceramics

CaCu 3 Ti 4 O 12 /CaTiO 3 (CCTO/CTO) composite ceramics were prepared through in-situ reaction and solid-state sintered at 1040°C for 10 h. The phase composition, microstructure, morphology, valence, and electrical properties of ceramics are systematically studied by X-ray diffraction(XRD), Field emission scanning electron microscopy(FESEM), Electron probe micro-analysis (EPMA), X-ray photoelectron spectroscopy(XPS), and LCR instruments. It can be found that the FESEM image shows that the addition of CTO inhibits the growth of CCTO grains, and there are nanocrystals inside the grains. The EPMA mapping demonstrated which nanocrystals are composed of CCTO and a small amount of CTO. Impedance spectroscopy observed two semi-circular arcs, which correspond to the effects of micron-level grains and nano-level nanocrystals, respectively. These two mechanisms significantly affect the colossal dielectric response of CCTO/CTO composite ceramics.